The present invention relates primarily to a double-drum winch for use with a side crane in a construction machine, and more particularly, to a double-drum winch of the type described above in which a hook drum for actuating the hook of the winch apparatus and a boom drum for actuating the boom means supporting the hook are actuated independently from each other.
Heretofore, a double-drum winch apparatus has been developed for actuating the hook and the boom means supporting the hook. In the prior art double-drum winch, however, the so-called horizontal retraction or horizontal extension of the hook, i.e., the operation by which the hook is moved downwardly or upwardly by the actuation of one of the drums or the hook drum while, at the same time, the boom means is actuated upwardly or downwardly by the actuation of the other drum or the boom drum, can not be effected, because the two drums can not be actuated independently from each other, thereby extremely limiting the range of the kinds of operations of the winch. Further, in the prior art winch apparatus, a number of operating levers are provided for the various operations of the winch thereby requiring skill of the operator while tending to cause false function of the winch and early fatigue of the operator.
The present invention aims at avoiding the disadvantages of the prior art winch as described above.